Ultrasound-assisted digestion of biodiesel samples for determination of metals by stripping voltammetry

Freitas, Helieder Cortes; Almeida, Eduardo Santos; Tormin, Thiago F.; Richter, Eduardo M.; Muñoz, Rodrigo A.A.

doi:10.1039/c4ay02313g

Cited by 23 publications

(20 citation statements)

References 36 publications

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“…Electrochemical stripping techniques have been applied in the determination of trace metal ions in crude oil, diesel oil, biodiesel and petroleum‐based products 5–9. Due to the highly organic nature of the samples, digestion is required to release metal ions and to decompose the organic matrix 5.…”

Section: Introductionmentioning

confidence: 99%

“…Due to the highly organic nature of the samples, digestion is required to release metal ions and to decompose the organic matrix 5. Sample preparation protocols employing dry ashing and wet digestion are the typical choice due to the simple instrumentation required; however, alternative methods have been proposed searching for high‐speed treatments and safer conditions for the analyst 5–9.…”

Section: Introductionmentioning

confidence: 99%

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Voltammetric Determination of Pb, Cu and Hg in Biodiesel Using Gold Screen‐printed Electrode: Comparison of Batch‐injection Analysis with Conventional Electrochemical Systems

et al. 2015

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This article compares the use of batch‐injection analysis (BIA) with a conventional batch system for the anodic stripping voltammetric (ASV) determination of Pb, Cu and Hg in biodiesel using screen‐printed gold electrode (SPGE). The optimized BIA conditions were 200 µL of injection volume of the digested samples at 5 µL s−1 directly on the working electrode of the SPGE immersed in 0.1 mol L−1 HCl solution. Therefore, BIA‐ASV presented the advantages of low sample consumption, which extended the SPGE lifetime to a whole working day of analyses, and potential for on‐site analysis using battery‐powered micropipettes and potentiostats. Although presenting lower sensitivity than conventional systems, the BIA‐ASV presented detection limit values of 1.0, 0.5 and 0.7 µg L−1, respectively for Pb, Cu and Hg, a linear range between 20 and 280 µg L−1, and adequate recovery values (90–110 %) for spiked biodiesel samples.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Voltammetric Determination of Pb, Cu and Hg in Biodiesel Using Gold Screen‐printed Electrode: Comparison of Batch‐injection Analysis with Conventional Electrochemical Systems

et al. 2015

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“…Microwave-assisted methods for sample preparation have been preferred over traditional digestion procedures due to decrease in time of analysis, reduced contamination from external sources and losses of volatile elements [9][10][11][12][13]. An elegant alternative to microwave-assisted methods is based on the use of ultrasound energy for sample preparation mainly using ultrasonic baths, which are operated at room-temperature and atmospheric-pressure, employ lower amount of concentrated acids and large sample amounts, and are typically faster [14][15][16][17][18]. The use of sonication for metal extraction from fertilizers have been reported recently in the literature using either ultrasonic baths [8,19,20] or high-power ultrasonic probes [21].…”

Section: Introductionmentioning

confidence: 99%

Combination of sonication and heating for metal extraction from inorganic fertilizers prior to microwave-induced plasma spectrometry determinations

Lima

Richter

et al. 2016

Applied Acoustics

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“…Moreover, samples were prepared according to the procedure described by Freitas et al, 26 with minor modifications. A total of 0.2 mL of biodiesel samples were treated with 1.9 mL of HCl 37% (m/v) and 1.9 mL of 30% H 2 O 2 (m/v); under ultrasonic conditions for 30 min.…”

Section: Sample Preparation and Analysismentioning

confidence: 99%

Development of a Novel and Simple Electroanalytical Procedure for the Determination of Copper in Biofuel Employing a Sensor Based on Vulcan Functionalized with Carbazone

Freitas¹,

Lima²,

Marques³

et al. 2018

J. Braz. Chem. Soc.

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A novel and simple electroanalytical method for the determination of Cu 2+ in biodiesel samples by stripping voltammetric analysis was developed. The method employs a carbon paste electrode (CPE) modified with Vulcan carbon, previouly functionalized with carbazone (CBZ). The CPE/Vulcan-CBZ sensor promoted a significant increase in the analytical signal obtained from copper as compared to unmodified CPE, and the CPE modified with Vulcan carbon (CPE/ Vulcan). Vulcan-CBZ, Vulcan and CBZ materials were characterized by Fourier transform infrared spectroscopy (FTIR) technique. The electrochemical behavior of the sensor was evaluated using cyclic voltammetry (CV) and square-wave anodic stripping voltammetric (SWASV) techniques. The CPE/Vulcan-CBZ modified electrode showed excellent response and was able to detect Cu 2+ at nanomolar levels. The electrochemical method is based on preconcentration of Cu 2+ ions on the CPE/Vulcan-CBZ at 0.35 V vs. Ag/AgCl(sat) in 0.2 mol L -1 ammonium sulfate solution ((NH 4 ) 2 SO 4 ), pH 3.5, during 120 s, followed by subsequent chemical stripping. The analytical signal showed a linear response for Cu 2+ concentrations in the range from 6 to 190 nmol L -1 (r = 0.998), with a detection limit of 1.2 nmol L -1 . The sensor was successfully applied for the determination of Cu 2+ in biodiesel and the average recovery varied between 97.0 and 102.8% for the soybean biodiesel samples and between 109.6 and 111.0% for the babassu biodiesel samples showing a good accuracy for the proposed method.Keywords: biofuel, copper, voltammetric sensor, Vulcan carbon, carbazone IntroductionThe pursuit of alternative fuels has been acquiring prominence in the last decades. The replacement of fossil fuels has been motivated by environmental, economical and social factors, since society itself depends on its use. In this context, one alternative that has stood out is the use of biofuels, such as charcoal, alcohol, biogas and biodiesel. 1,2 Biodiesel is a renewable fuel produced either from vegetable sources (soybean, castor oil, palm oil, sunflower, among others) or from ethanol (from sugarcane) or methanol (which can be obtained from wood biomass). 3 It is, therefore, a biodegradable, sustainable and environmentally friendly fuel. However, some metals, such as Cu, Fe, and Ni, can be inserted in the production process with the catalysts, during transportation and storage. Furthermore, the presence of these metals, even at trace levels, can promote the formation of gums and sediments that damage vehicle engines and promote the oxidation of biodiesel. 4,5 Copper, iron and the effect of nickel on biodiesel's stability has been widely evaluated. Among these metals, copper is the most powerful catalyst in biodiesel's oxidation process. 5 Therefore, the monitoring of the amount of copper is extremely important in this fuel for preventing undesirable variations in its physical state and properties, during its use or storage. 5 In this context, it is opportune and necessary to develop novel sensitive and selective anal...

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Ultrasound-assisted digestion of biodiesel samples for determination of metals by stripping voltammetry

Abstract: Room-temperature ultrasound-assisted digestion of biodiesel for stripping voltammetry of metals with adequate recovery values (94–108%) and low residual carbon content is demonstrated.

Cited by 23 publications

References 36 publications

Voltammetric Determination of Pb, Cu and Hg in Biodiesel Using Gold Screen‐printed Electrode: Comparison of Batch‐injection Analysis with Conventional Electrochemical Systems

Voltammetric Determination of Pb, Cu and Hg in Biodiesel Using Gold Screen‐printed Electrode: Comparison of Batch‐injection Analysis with Conventional Electrochemical Systems

Combination of sonication and heating for metal extraction from inorganic fertilizers prior to microwave-induced plasma spectrometry determinations

Development of a Novel and Simple Electroanalytical Procedure for the Determination of Copper in Biofuel Employing a Sensor Based on Vulcan Functionalized with Carbazone

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